Load shifting mechanism for power vehicles



June 2, 1936. w. FERRIS LOAD SHIFTING MECHANISM FOR POWER VEHICLES 3Sheets-Sheet 1 INVENTDR' WALTER F EHH'IS Original Filed Jan. 30, 1933ATTORNEY.

June 2, 1936. w FE s 2,042,519

LOAD SHIFTING MECHANISM FOR POWER VEHICLES Original Filed Jan. so, 19555 Sheets-Sheet 2 INVENTEIR WALTER FERRIS BY ATTORNEY.

June 2, 1936. w FERR|5 I 2,042,519

LOAD 'SHIFTING MECHANISM FOR POWER V-E-HICLES Original Filed Jan. so,1933 3 Sheets-Sheet s INVENTDH WA LTEF? F EH ms ATTUF'N EY.

Patented June 2, 1936 UNITED FSTI'ATES PATENT OFFICE LOAD SHIFTINGMECHANISM FOR POWER VEHICLES -.Walter :Ferris, Milwaukee, Wis., assignorto The Oilgear Company, Milwaukee, Wis.,-a corporation ;of"Wisconsin ber9, .1934, Serial-No.

'21 Claims.

This invention relates to power vehicles ofthe type employed to exerttractive .forces upon independently supported loads, such 'as the powervehicle described and claimed in Patent No. 2,037,373 which issued April14, 1936 on application Serial No. 654,157, filed January30, .1933, ofwhich this application is a division.

A power vehicle orlocom'otive is ordinarily so constructed that itsweight isequally distributed upon the several .pairs of driving wheelswhen the vehicle is stationary but, when the vehicle is started underits own power or when it is exerting a tractive force upon anindependentlycsupported load, a part of the-weight carried by the frontwheels of eachself-propelled truck is shifted to the rear wheels-of.that'truok due to the fact that the center of gravity of'the masses tobe accelerated and the draw bar ;pull'are .in much higher planes thanthe tracks upon which tractive force is exerted by the wheels.

Thistransfer of 'weight'reduces the traction of the front wheels. andcauses them to slip before the rear wheels slip when axhigh rotativeforce is applied to the wheels during the "starting period .or when thevehicle isattemptingto accelerate a heavy load.

-It. has heretofore been iproposed to apply .an independent loading:force to :the front wheels of a :power vehicle during'the startingperiod but no provision has been #made for applying such a force duringcontinued operation :of the vehicle or for varying that forceinzaccord'ance with variations in the tra'ctive efiort of theengine orother propelling means.

The present invention has'assan object'to provide a power vehicle inwhichithe weight shifting effect of the propelling force .iscounteracted throughout the entire (period during which the vehicle isin operation.

Another object is to provide a power vehicle with means for exertinganindependentloading force upon the wheels from whichthe propellingforce tends'to shift'weightand for varying the loading force accordingto variations-in the propelling force.

Another object is to "provide a power vehicle with a load-transferring:mechanism which vis operated automatically in response zto: operationof the engine or motor employed to :drive the vehicle. 7

Another objectis to provide a power vehicle with a load-transferringmechanism which .is simple in construction, sturdy, .and :positivelnoperation.

Otherobjects. and "advantages-will. appear. from the descriptionhereinafter given of an illustrativeembodiment of the invention.

According to the invention in a general aspect, a load-transferringmechanism is arranged at the front end of a vehicle truck and energizedduring the entire time the vehicle is in opera: tion.

According to'the invention in a more particular aspect, theload-transferring mechanism is energized by the power means whichenergizesthe driving motor.

According to theinvention in another aspect, the body of the vehicle issupported upon a truck by a 'bearing which is :arranged nearer to oneaxleof the truck than to the other axle thereof, and. an independentloading force is applied to the axle which'is fartherfrom-thebearingawhenever the vehicle is moving in a direction tom'akethat Fig. 2 is in part an end view 'of' one of the-locomotive trucksrand-in -part a transverse. section showin'g'a cylinder and pistonbyzmeans of which an individual loading force may beapplied to one of.the' truck axles, the view being taken approximately along theirregular line 22 of Fig. 1.

Fig. :3 'is.a "sectional elevation .of one of the trucks taken 1approximately @along :the irregular line -3:3 *of *Fig.' 2.

Fig. 4 is a diagram illustrating .theazhydraulic circuit -:.of -.thelocomotive :and showing the relation of itheload-transferringr meanstothe motors which drive the locomotive.

The locomotive. has not been fully'illustrated norwilliitbedescribediin'detail for the reason thatfit is fully .illustratedanddescribed in the 'application'referred' to a above.

Briefly, it is provided with a body I which is supported upon twotrucksland 2 'an'dcarries two internal combustion :engines 2-3 .and 13 and two.creversiblexpumps land which are driven, respectively, .by the-engines3 and 3 The trucks 2 and 2 are identi'cal but arearrangediin reverseposition beneath the :body I.

isxone .truckiisiturned end for endlinrrespectfto the other'truck.

The .Llocomotivezis: symmetrical about? its transverse ;centerlinefand,in: order that corresponding parts i may be ;rea'dily distinguished, ithe parts :on one side :of the centerline'zhave been designated bycertain reference numerals and the corresponding parts on the other sideof the centerline have been designated by the same reference numeralswith the exponent a added.

The body I is supported on each of the trucks by a center bearingconsisting of a post 5, which is rigidly anchored in the frame of thetruck and has a spherical upper end, and a socket 6 which is fitted uponthe spherical upper end of the post 5 and rigidly secured to the frame Iupon the under side thereof.

Each truck is supported at one end by two wheels fixed on an axle 1 andat the other end by two Wheels fixed on an axle 8. As shown in Fig. 3,the axle I is driven by avariable displacement rotary hydraulic motor 9through single reduction gearing I ll-I I, and the axle 8 is driven by avariable displacement rotary hydraulic motor I2 through double reductiongearing I3-I4I5.

Under certain conditions of operation, the motors 9 and I2 aresimultaneously supplied with liquid from the pumps 4 and 4 so that thetorque of the two motors is the same. Consequently, the motor I2 willoperate at a higher speed than the motor 9 and will exert a greaterrotative force upon the axle 8 than the motor 9 exerts upon the axle 1due to the fact that the ratio of the gearing I 3I 4 I5 is muchgreaterthan the ratio of the gearing II I.

. The motors 9 and I2 are driven by liquid supplied thereto from thepumps 4 and 4 The direction in which the motors are driven depends uponthe direction in which liquid is delivered thereto, and the speed atwhich each motor is driven depends upon its displacement and upon therate at which the liquid is delivered.

The displacement of the motor 9 is varied by a cam wheel I6 (Fig. 3)acting through a bell crank lever I! which has one of its arms connectedby a pin and slot connection to the stroke-changing element of the motorand its other arm provided with a roller and urged by a spring I8 in adirection to decrease motor displacement, the spring I8 holding theroller against the periphery of the cam wheel I6.

Thedisplacement of the motor I2 is varied by a cam wheel I9 actingthrough a bell crank lever 20 which has one of its arms connected by apin and slot connection to the stroke-changing element of the motor andits other arm provided with a roller and urged by a spring 2| in adirection to decrease motor displacement, the spring 2| holding theroller against the periphery of the cam wheel I9.

The cam wheels I6 and I9 may be rotated simultaneously by a controlshaft 22 (Fig. 3) which is connected by suitable'gearing to the shaftsupon which the cam wheels I6 and I9 are fixed. The shaft 22 is connectedthrough suitable shafting and gearing to a hand wheel 23 (Fig. 1)arranged at one end of the body I, universal joints being arranged inthe shafting to provide for the trucks pivoting beneath the body whenthe locomotive travels around a curve. The motors .on the truck 2 aresimilarly controlled from the same hand wheel so that all motors may bead- J'usted simultaneously. 7 The contours of the cam wheels I6 and I9are such that, during rotation of the hand wheel 23, the displacement ofthe motor I2 is gradually reduced faster than the displacement of themotor. 9 until it is at a predetermined minimum at which time it issuddenly reduced to zero and short-'circuited, and the displacement ofthe motor 9 is simultaneously increased by a like amount as fullyexplained in the application referred to above. Thereafter, thedisplacement of the motor 9 may be gradually reduced until it is at apredetermined minimum.

The delivery of liquid to the motors is controlled by varying the rateand the direction of delivery from the pumps 4 and 4 each of which hasits displacement varying mechanism connected by suitable linkage to alever 24 arranged at one end of the body I.

When the lever 24 is in its central or neutral position, the pumps areat zero stroke and no liquid is being delivered thereby. When the lever24 is moved in one direction or the other from its neutral position, thepumps will deliver liquid in one direction or the other and at a ratedepending upon the direction and the distance the lever 24 is moved fromits neutral position.

In starting the locomotive from a stationary position, at which time thepumps 4 and 4 are at zero stroke, the control wheel 23 is operated toadjust the motors to full stroke in order that they may have the highesttorque and then the control lever 24 is operated to adjust the pumps andcause them to deliver liquid at a limited volumetric rate to the motorswhereby the full power of the engines 3 and 3 is available for operatingthe motors at slow speed and enabling them to exert high rotative forcesupon the driving wheels and thereby start the locomotive and its load.

After the locomotive has been started, the control lever 24 may beoperated to increase pump displacement and thereby increase the speed ofthe locomotive until the pumps are at full stroke and then the controlwheel 23 may be operated to reduce motor displacement and therebyfurther increase the motor speed with the resultant increase in thespeed of the locomotive.

When the lever 24 has been moved to the point where the displacement ofthe high speed motor I2 has been reduced to the predetermined minimum,the motor is operating at approximately the highest speed for which itis designed to work with its pistons reciprocating and transmittingpower. For higher locomotive speeds the high speed motors should beshort-circuited and returned to zero stroke, in which condition they arein perfect balance and relieved of load, and can spin freely at higherspeeds as the locomotive is driven faster by the other motors. Furthermovement of the lever 24 causes the high speed motor on each truck to besuddenly adjusted to zero displacement and short-circuited, and theentire output of the pump to be directed to the other two motors. Stillfurther movement of the lever 24 reduces the displacement of these twomotors and further increases the speed of the locomotive.

Liquid for operating the motors is delivered by the pumps 4 and 4 into apipe 25 or into a pipe 26 (Fig. 4) depending upon the direction in whichthe lever 24 is moved from its neutral position. The pipes 25 and 26 areconnected, respectively, by pipes 21 and 28 to the socket of the centerbearing on the truck 2 and by pipes 21 and 28 to the socket 5 of thecenterbearing on the truck 2.

The pipes 21 and 28 are connected to the socket 5 in communication,respectively, with fluid channels 29 and 30 extending through the centerbearing 5-6 which, in addition to supporting the body I upon the truck2, functions as a flexible connection for the delivery of liquid to themotor as-explained in the a'pplicationrferred to above.

'The channels 29 and 30-are connected, respectivelyjbytvro pipesdland 32tothe two ports 6f the-motor!) andbytwo pipes-' 33- and 34to-ava1ve 35through-'which'liquidis delivered to=the motor I2 and by means of-whic'h-the motor 42 is shortcircuited.

" The center b'earing on the truck 2 is' provided with channels 29 and30 which 'correspondtothe channels 29 and'dll in the centerbearing onthe truck 2. The motors 9 and 'I'Z -on the truck "2 are connectedto'thechannels' 2E|* -'ancl"30 by connections which correspondetotheabove describedconnections an'd which have been designated bycorresponding referencenumeralswith the exponent "a added. However,since the truck 2 is turned end for end in respect to the With thisarrangement, bothof'the pumps deliver liquid simultaneously to'themotors on both 'of the trucks so that equalvolumes of liquid aredelivered atthe same pressure'to the-motors on both trucks.

When the motors are eneig'ized'to propelthe locomotive, the inertia 'ofthe body I andthe tractive force-exerted by the locomotive tends toshift weight from the leading axle of each truck 'to the 'followingaxleof that truck in respect to the direction of movement for the reasonthat thedraw'bar pulland the-center of gravity of 'the acceleratedmasses arein muchhigher planes thanthe rails which-exert-thetractiveforce on the wheels. The: amount of weight thus shifted is proportionalto thetractive forceexerted by --the locomotive, and the tractive''forcee is proportional to the working pressure' existing innthe liq-.uid which drives the motors.

'If no provision were made for-counteractingthis*weight-shiftingl'efiect, the front Wheels of each truck would sliplong before the motors had "exerted amaximum'rotative.forceupon the rearwheels, thereby -materially limiting the tractive effort of thelocomotive.

slippage of the'front'wheels may be prevented by exerting an independentloading force upon the front axle of each truck in :response to atractive effort of the locomotive'or by -:so supporting the locomotivebody upon the truck:that the front axle of each truck'carries a'greaterweight than the rear axle when the locomotive is idle so that, when thelocomotive isstarted or is exerting a tractive effort upon anindependently supported load, the-weight shifted fromthe front axle tothe rear axle will approximately equalize the load upon-the twee-axlesat the maximum draw bar pull and enable'both the front and the rearwheels to have suflicienttraction to start the locomotive or to move anindependently supported load.

If unequal loading of-the axles weresolely .depended upon toprevent'wheel-r slippage, it is obvi- -.ous that all of the wheels wouldhave sufficient traction only when the .locomotive was "operated 'in butone direction while, if the application of an independent'loading forceto the front axles were solely'depended upon to prevent wheel slippage,it would be necessary to provide mechanisms for selectivelyexerting'independent loading'- forces upon=all axlesin order'thattlieloco- :motive might (operate in either direction and all of it's' whelshave 'suficient traction iin either. direction of operation.

In order that the number i of mechanisms for exerting independentloading "forces upon the axlesmay be kept ata minimum ina locomotivewhich is operable ineither direction, theflocomotive body issupporte'dupon each truck ata point nearer to one a-xle than to theother axle so that 'the nearer axle of each truck-carries a greater loadthan the 'far axle whenthe locomotive is idle, a loadingmechanismis'provlde'd for exertinglan independent' loading 'force upon the faraxle of each-truck,'-andonly one of those loading mechanisms isenergized at a time; the one energized depending upon .thedirection inwhich the locomotive moves or tends *to' move.

As shown, the center bearing'lS-Son'the truck Z-i'sarranged nearertheaxle'l'than tothe axle 8, a hydraulic jack 3'6 is secured to the bodyI above the axle 8 to exert an independent loading force thereonwheneverthe locomotive tends to move in a direction which makes the axle'8 the leading axle,-the truck 2 is turned-end for'end so that the=twoend a xles l and l carry greater loads than the center =axles-8 and 8*when the locomotive is idle, and a hydraulic jack 36 is secured to thebody l above the axle 8 to exert an independent loading force thereonWhenever the locomotive'tends to move in a direction which makes theaxle B the leading axle. Of course, the arrangement could be reversed'so that the center bearings would be arranged nearer the center axles 8and 8 and the jacks36'and 36 would be-arranged above the end axles ,land "l The jack35 consists primarily of a cylinder and a piston 38fitted therein-and provided upon its lower end with a roller 39 toengage a'bearing plate '49 fixed between two beams 'M which ex- .tendacross-the endof the truck 2 and are sup- :pcrted uponitheside-frames'thereof.

The cylinder 3'! is-fastened to the body 1 upon the-under side thereoias *by being secured between two channel -bars-4'2 which extend acrossthe body I and are fastened to the side sills thereof. The 'jack 35issimilarly constructed and "arranged. j

The jack 3% is connected attheupper'end of .its cylindertlto thepipe'ZSby a-pipe 4 3 and the jacket is connected at the upper end ofitscylinder tl to 'the pipeZl bye-pipe 13%:50 that jack 36 will beenergized wheneverdriving liquid is delivered to the motors throughthe'pipeZB 'andjack 35 -will be energizedwhenever driving liquid isbeing delivered to the :motors through pipe zl "When the pumps ".4 and 4deliver liquid :to the driving motors'ithrough pipes 28 and 28?,xthe"motors will'move the. locomotive towardttherright in respect to Fig. 1and liquid will be returned -=tothe pumps-throughpipes 2-1 *and 21*.Therefore, high pressure prevailsin'pipe r28.so.that the jack 36 is.enabledto exert a loading force upon the axle 8, and'low'pressureprevails'in pipe 2!- so'that the jack 3B isinactive.

The tractive effort :of the locomotive causes weight to be shifted'fromthe heavily loaded .leadingaxle 1 ZtO .thevmore lightly loaded fol-.lowing axlefle, so:that theaxles oftthetruck 2 a are more evenlyloaded-Jandxtendstofcause weight caused by placing the'center bearingnearer the axle 1 than to the axle 8.

Since the jack 36 is connected to the high pressure side of the pump andsince the pressure of the liquid is always proportional to the tractiveforce, the loading force exerted upon the axle 8 will always beproportional to the tractive force, and always suificient to preventslipping of the front wheels at the existing working pressure. When thepressure reaches the maximum, the loads on the near and far axles willbe equal, or in any ratio to each other which may be provided for in thedesign of jacks 36-36.

When thepumps 4 and 4 deliver liquid to the driving motors throughpipes. 21 and 21 the motors will move the locomotive toward the left inrespect to Fig. 1 and liquid will be returned to the pump through pipes28 and 28*. Therefore, conditions will be exactly reversed from thoseabove described. That is, the jack 36 will be energized and the jack 36will be inactive.

The invention herein set forth is susceptible of various modificationswithout departing from the scope thereof as hereafter claimed.

The invention is hereby claimed as follows:

1. In a power vehicle, the combination of a body, a truck arrangedbeneath said body to support the same and having a plurality of axleswith wheels thereon, the weight carried by said truck being distributedin a definite ratio between said axles, power means for driving one ormore of said axles, a draw bar so positioned that tractive force exertedtherethrough shifts a part of the load from one axle to another, andmeans automatically operated by said power means to counteract the loadshifting effect of a force exerted through said draw bar. r

2. In a power vehicle, the combination of a body, a truck having twoaxles and carrying a part of the weight of said body and so arrangedthat the weight carried thereby is distributed unequally between saidaxles, power means for driving one of said axles, and means operated bysaid power means for automatically increasing the load upon said powerdriven axle in response to said power means driving said axle in a givendirection.

3. In a power vehicle, the combination of a body, a truck having aplurality of axles and carrying a part of the weight of said body and soarranged that the weight carried thereby is distributed unequallybetween said axles, power means for driving one of said axles, and meansresponsive to said power means driving said axle in a given directionfor automatically exerting an independent loading force upon said powerdriven axle andfor varying said force according to variations in theforce exerted by said power means. 7 V

4. In a powervehicle, a body, a truck arranged beneath said body andhaving two axles with wheels thereon to support the same, a supportcarried by said truck for supporting at least a part of the weight ofsaid'body, said support being arranged nearer to one axle than to theother axle, separate power means for driving each of said axles, andload-transferring means for increasing the load upon the more distantaxle in responsetosaid power means moving said vehicle in a directionwhich makessaid-more distant axle the leading axle, V

5. In a power vehicle, a truck having front and rear wheels, powermeansfor rotating said wheels to drive said vehicle and enable it to exert atractiveforce upon anindependently supported load whereby said tractiveforce tends to-shift weight from said front wheels to said rear wheels,and means operated by said power means for exerting an independentloading force upon said front wheels in response to said power meanstending to move said vehicle forward.

6. In a power vehicle, a truck having front and rear wheels,hydraulic-power means for rotating said wheels to drive said vehicle andenable it to exert a tractive force upon an independently supported loadwhereby said tractiveforce tends to shift weight from said front wheelsto said rear wheels, and hydraulic means operated by said power meansfor exerting an independent loading force upon said front wheels inresponse to said power means tending to move said vehicle forward.

'7 In a power vehicle, a truck having front and rear wheels, power meansfor rotating said wheels to drive said vehicle and enable it to exert atractive force upon an independently supported load whereby saidtractive force tends to shift weight from said front wheels to said rearwheels, and means responsive to said power me'ans tending to move saidvehicle forward for exerting an independent loading force upon saidfront wheels and for varying said loading force in accordance withvariations in said tractive force.

8. In a powervehicle, a body, a plurality of wheels for supporting saidbody, power means for rotating said wheels to drive said vehicle ineither direction and enable it to exert a tractive force upon anindependently supported load whereby said tractive force tends to shiftweight from the front wheels to the rear wheels in respect to thedirection of movement, and means operated by said power means andresponsive to said power means tending to operate said vehicle in eitherdirection for counteracting the weight shifting effect of said tractiveforce in either direction of operation of said vehicle.

9. In a power vehicle, a body, a plurality of wheels for supporting saidbody, power means for rotating said wheels to drive said vehicle ineither direction and enable it to exert a. tractive force upon anindependently supported load whereby said tractive force tends to shiftweight from the front wheels to the rear wheels in respect to thedirection of movement, and means responsive to said power means tendingto operate said vehicle in either direction for exerting an independentloading force upon said front wheels in either direction of operation ofsaid vehicle and for maintaining said loading force proportional to saidtractive force.

10. In a power vehicle, the combination of a body, a truck arrangedbeneath said body to support the same and having a plurality of axleswith wheels thereon, the weight carried by said truck being distributedin a definite ratio between said axles, a hydraulic motor for driving anaxle, a pump for supplying motive fluid to said motor, a draw bar sopositioned that tractive force exerted therethrough shifts a part of theload from one axle'to another, a hydraulic jack arranged between saidbody and said truck above the axle from which a part of the load isshifted by said tractive force, and means connecting said jack to saidpump in parallel with said motor;

11. In a power 'vehicle, a body, a truck arranged beneath saidbody andhavingtwo axles with wheels thereon to support the same, a supportcarried by Said truck for supporting at least a part of the weight ofsaid body, said support 'tends to move an independently supported load,and load-transferring means for increasing the being arranged nearer toone axle than to the other axle, separate hydraulic motors for drivingeach of said axles with different tractive forces, the larger tractiveforce being imparted to the axle more distant from said support, pumpingmeans for supplying motive liquid to said motors, fluid channelsconnecting said motors to said pumping means and forming therewith ahydraulic circuit, load-transferring means for increasing the load uponthe more distant axle, and means connecting said-load-transferring meansto that side of said circuit which is the high pressure side when saidmotors are driving said vehicle in a given direction.

12. In a power vehicle, a truck having front and rear wheels, hydraulicdriving means for rotating said wheels to drive said vehicle and enableit to exert a tractive force upon an independently supported loadwhereby said tractive force tends to shift weight from said front wheelsto said rear wheels, pumping means for supplying motive .liquid to saiddriving means, fluid channels connecting said driving means to saidpumping means and forming therewith a hydraulic circuit, hydraulicload-transferring means for exerting an independent loading force uponsaid front wheels, and means connecting said load-transferring means tothat side of said circuit which is the high pressure side when saiddriving means is operating in a direction to move said vehicle forward.

13. In a power vehicle for moving independently supported loads, thecombination of a body, a truck arranged beneath each end of said body tosupport the same and provided with two axles, a bearing carried by eachtruck for supporting said body thereon, one bearing being arranged atone side of a point midway between the axles of one truck and the otherbearing being arranged at the other side'of a point midway between theaxles of the other truck whereby the axle nearer each bearing carries agreater load than the more distant axle when said vehicle is stationary,power means for rotatingsaid axles ineither direction 'to enable saidvehicle to exert a tractive force in either direction upon anindependently supported load, said tractive force tending to shift apart of the load carried by the leading axle to the following axle inrespect to the direction in which said vehicle tends to move anindependently supported load, and load-transferring means for increasingthe load on'the more distant axle of either truck whenever that axle isthe leading axle.

14. In a power vehicle for moving independently supported loads, thecombination of a body, a truck arranged beneath each end of said body tosupport the same and provided with twoaxles, a bearing carried by eachtruck for supporting said body thereon, one bearing being arranged atone side of a point midway between the axles of one truck and the otherbearing being arranged at the other side of a point midway between theaxles of the other truck whereby the axle nearer each bearing carries agreater load than the more distant axle when said Vehicle is stationary,power means for applying different rotative forces to the axles of eachtruck to rotate said axles in either direction and thereby enable saidvehicle to exert a tractive force in either direction upon anindependently supported load, said tractive force tending toshift a partof the load carried by the leading axle to the following axle in respectto the direction in which said vehicle load on the more distant axle ofeither truck whenever that axle is the leading axle.

15. In a power vehicle for moving independently supported loads, thecombination of a body, a truck arranged beneath each end of said body tosupport the same and provided with two axles,

a bearing carried by each truck for supporting said body thereon, onebearing being arranged at one side of a point midway between the axlesof one truck and the other bearing being arranged at the other side, ofa point midway between the axles of the other truck whereby the axlesnearer each bearing carries a greater load than the more distant axlewhen said vehicle is stationary, power means for rotating said axles ineither direc L.

tractive force in either direction upon an independently supported'load,said tractive force tending to shift .a part of the load carried by theleading axle to the following axle in respect to the direction in whichsaid vehicle tends tomove an independently supported load, andload-transferring means operated by said power means for increasing theload on the more distant axle of either truck whenever that axle is theleading axle. w

16. In a power vehicle for moving independently supported loads, thecombination of a body, a truck arranged beneath each end of said body tosupport the same and provided with two axles, a bearing carried by eachtruck for supporting said body thereon, one bearing being arranged atone side of a point midway between the axles of one truck and the otherbearing being arranged at the other side of a point midway between theaxles of the other truck whereby the axles nearer each bearing carries agreater load than the more distant axle when said vehicle is stationary,hydraulic power means for rotating said axles in either direction toenable said vehicle to exert a tractive force in either direction uponan independently supported load, said tractive force tending to shift apart of the load carried by the leading axle to the following axle inrespect to the direction in which said vehicle tends to move anindependently supported load, and hydraulic load-transferring means forincreasing the load on the more distant axle of either truck wheneverthat axle is the leading axle.

17. In a power vehicle for moving independently supported loads, thecombination of a body, a truck arranged beneath each end of said body tosupport the same and provided with two axles, a bearing carried by eachtruck for supporting said body thereon, one bearing being arranged atone side of a point midway between the axles of one truck and the otherbearing being arranged at the other side of a point midway between theaxles of the other truck whereby the axle nearer each bearing carries agreater load than the more distant axle when said vehicle is stationary,hydraulic power means for applying different rotative forces to theaxles of each truck to rotate said axles in either direction and therebyenable said vehicle to exert a tractive force in either direction uponan independently supported load, said tractive force tending to shift apart of the load carried by the leading axle to the following axle inrespect to the direction in which said vehicle tends to move anindependently supported load, and hydraulic load-transferring means forincreasing the load on the more distant axle of either truck wheneverthat axle is the leading axle.

18. In a power vehicle for moving independently supported loads, thecombination of a body, a

truck arranged beneath each end of said body to support the same andprovided with two axles,

a bearing carried by each truck for supporting said body thereon, onebearing being arranged at one side of a point midway between the axlesof one truck and the other bearing being arranged at the other side of apoint midway between the axles of the other truck whereby the axlenearer each bearingcarries a greater load than the more distant axlewhen said vehicle is stationary, hydraulic power means for rotating saidaxles in either direction to enable said vehicle to exert a tractiveforce in either direction upon an independently supported load, saidtractive force tending to shift a part of the load carried by theleading axle to the following axle in respect to the direction in whichsaid vehicle tends to move an independently supported load, a hydraulicjack arranged between said body and each truck above the axle moredistant from the bearing on that truck for increasing the load upon saidmore distant axle, and means for supplying pressure fluid to one jack orthe other in response to said power means driving said axles in onedirection or the other.

19. In a power vehicle for moving independently supported loads, thecombination of a body,

a truck arranged beneath each end of said body .each bearing carries agreater load than the more distant axle when said vehicle is stationary,hydraulic power means for rotating said axles in either direction toenable said vehicle to exert a tractive force in either direction uponan independently supported load, said tractive force tending to shift apart of the load carried by the leading axle to the following axle inrespect to the direction in which said vehicle tends to move anindependently supported load, a hydraulic jack arranged between saidbody and each truck above the axle more distant from the bearing on thattruck for increasing the load upon said more distant axle, means forsupplying pressure fluid to one jack or the other in response to saidpower means driying said axles in one direction or the other, and meansfor permitting each truck to pivot freely beneath said body during thetime said jack is increasing the load upon said more distant axle.

20. In a power vehicle for moving independently supported loads, thecombination of a body, a truck arranged beneath each end of said body tosupport the same and provided with two axles, a bearing carried by eachtruck for supporting said body thereon, one bearing being arranged atone side of a point midway between the axles of one truck and the otherbearing being arranged at the other side of a point midway between theaxles of the other truck whereby the axle nearer each bearing carries agreater load than the more distant axle when said vehicle is stationary,hydraulic motors for rotating said axles in either direction to enablesaid vehicle to exert a tractive force in either direction upon anindependently supported load, said tractive force tending to shift apart of the load carried by the leading axle to the following axleinrespect to the direction in which said vehicle tends to move anindependently supported load, pumping means, fluid channels connectingsaid motors to said pumping means and forming therewith a hydrauliccircuit, means for reversing the flow of liquid in said circuit, and ahydraulic jack connected to said hydraulic circuit and arranged betweensaid body and each truck above the axle more distant from the bearing onthat truck for increasing the load on said more distant axle, one ofsaid jacks being connected to one side of said circuit and the otherjack being connected to the other side of said circuit whereby one ofsaid jacks is automatically energized upon said vehicle being driven ineither direction.

21. -In a power vehicle, a body, a truck arranged beneath said body andhaving two axles with wheels thereon to support the same, a supportcarried by said truck for supporting at least a part of the weight ofsaid body, said support being arranged nearer to one axle than to theother axle, separate power means for driving each of said axles withdifferent rotative forces, the larger v

